Device with tensioners

ABSTRACT

This disclosure provides for a medical device to be implanted in the vasculature and a method for treatment in the vasculature. The device has an outer layer of a first material and an inner layer of a second material attached to the outer layer. The inner layer further has a plurality of elastomeric tensioners. If the device experiences relaxation, resulting in a decreased radial force against the vessel wall, the elastomeric tensioners may provide a contraction force to the inner layer and the outer layer, resulting in a maintained radial force on the vessel wall.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/291,384, which claims the benefit of priority under 35U.S.C. § 119(a) to U.S. Provisional Application No. 62/243,284, filedOct. 19, 2015, all of which are hereby incorporated by reference intheir entirety.

BACKGROUND 1. Technical Field Text

The present disclosure relates to medical devices. More particularly,the disclosure relates to a bioabsorbable device and method of treatmentwith the device.

2. Background Information

Often, physicians use vascular implantable devices to treat variousconditions. Such devices may be designed to exert a radial force againsta vein or body vessel having a vessel wall. In some cases, the vesselwall may be highly flexible. It may be advantageous for the device toaccommodate the natural environmental forces experienced by the vesselwall, while maintaining treatment capacity and vessel patency. Forexample, a vena cava filter may be used to treat pulmonary embolism andthrombosis.

Over time the device may experience relaxation or deformation, whichresults in a decreased radial force against the vessel wall. This mayresult in unintended migration of the device in the body vessel. In thiscase, it may be desirable to have a device that can maintain the radialforce against the vessel wall to avoid unintended migration.

After the device serves its intended purpose, the user may desire toremove the device. However, a secondary procedure to remove the devicemay result in unintended consequences. In some cases, it may beadvantageous to have a device that can maintain the radial force againstthe vessel wall during use and then be partially or completely removablewhen the intended use terminates.

BRIEF SUMMARY

The present disclosure provides generally for a bioabsorbableimplantable device. The disclosure also provides generally for a methodof treatment using said device. The device may be implanted in a bodyvessel with a vessel wall. The device may have a longitudinal axis thatmay run along the vessel's longitudinal axis. Generally, the device mayhave an outer layer, inner layer, and plurality of elastic tensioners.

The outer layer may be formed from a first material with a plurality ofouter cells. The plurality of outer cells may be arranged in outercircumferential rows with each outer cell having an outer perimeter.Each outer perimeter may have a first outer cell edge attached to asecond outer cell edge at a distal outer cell end, defining a distalouter angle, and a third outer cell edge attached to a fourth outer celledge at a proximal outer cell end, defining a proximal outer angle. Thedistal outer angle may be distal the proximal outer angle along thelongitudinal axis.

The inner layer may be formed from a second material being elastic orelastomeric. The inner layer may also contain a plurality of innercells. The plurality of inner cells may be arranged in innercircumferential rows with each inner cell having an inner perimeter. Theouter and inner layers may define a tubular body having a proximal endextending to a distal end and a lumen formed therethrough, the tubularbody being movable between a collapsed state for delivery and anexpanded state for treatment in the body vessel. The inner perimeter mayhave a first inner cell edge attached to a second inner cell edge at adistal inner cell end, defining a distal inner angle in the expandedstate, and a third inner cell edge attached to a fourth inner cell edgeat a proximal inner cell end, defining a proximal inner angle in theexpanded state. The distal inner angle may be distal the proximal innerangle along the longitudinal axis. At least one outer perimeter may beattached to at least one inner perimeter.

The plurality of tensioners may have an extended length and a contractedlength. The tensioners may be made of the second material with eachinner cell having one tensioner. Further, one tensioner may be attachedto the proximal inner cell end and may extend distally to the distalinner cell end to apply a contraction force on the one inner cell.

One tensioner may form a first angle with the first inner cell edge anda second angle with the second inner cell edge, the sum of the first andsecond angles may be about the same as the distal inner angle. The firstand second angles may be between about 25 to about 50 degrees each inthe expanded state.

The outer and inner layers may define a tubular body having a proximalend extending to a distal end and a lumen formed therethrough. Thetubular body may have a collapsed state for delivery and an expandedstate for treatment in the body vessel. The tubular body is movablebetween the expanded state and the collapsed state.

In the expanded state, the tensioners may have an extended length and acontracted length to maintain a radial force on the vessel wall. Forexample, the outer layer or tubular body lengthens or experiences alengthening force and the tensioners counter the lengthening force withthe contraction force to move from an extended length to a contractedlength to maintain a radial force on the vessel wall.

The second and third outer cell edges may form a first outer cell apexand the first and fourth outer cell edges may form a second outer cellapex. The second and third inner cell edges may form a first inner cellapex and the first and fourth inner cell edges may form a second innercell apex. In one embodiment, the outer and inner perimeters may berhombic. In another embodiment, the first and second outer cell apicesand the first and second inner cell apices are arcuate. Likewise, thefirst outer and inner cell apices are each about 80 degrees to about 130degrees in the expanded state and the second outer and inner cell apicesare each about 80 degrees to about 130 degrees in the expanded state.

The inner layer, outer layer, and tensioner may be a co-extrusion of thefirst and second materials. In addition, the first material may be ahigh mechanical strength material. The high mechanical strength materialmay be a material selected from the group consisting of a polyurethane,a polyester, a polyanhydride, a polylactide, poly-L-lactic acid,poly-L/D-lactic acid, and a co-polymer of poly lactic-co-glycolic acidand polycaprolactone. The elastomeric second material may containpolycaprolactone, the polycaprolactone content ranging from about 10percent to about 100 percent of the elastomeric material. In oneembodiment, the first and second materials may be biodegradable.

The device in any embodiment may further contain a plurality of filterstruts attached to the inner layer. In another embodiment, the devicemay contain a plurality of filter struts attached to the outer layer. Inanother embodiment, the device may contain a plurality of filter strutsattached to each of the inner layer and the outer layer. Each filterstrut may contain a proximal segment attached to the distal end andextending distally to a distal segment wherein all distal segments areattached to each other, gathered at a center point along thelongitudinal axis. The plurality of filter struts may be about six toabout twelve filter struts. The tubular body may have a length of about25 millimeters to about 60 millimeters between the proximal and distalends.

As one advantage to the device discussed herein, having an outer andinner layer allows the use of two different materials in the tubularbody. For example, if the first material is susceptible to relaxation,the inner layer may comprise a second material to aid in maintaining theradial force against the vessel wall. This advantage may be particularlyuseful with biodegradable materials as the first material. In addition,this advantage may be particularly useful within the vena cava, which ishighly flexible and may experience normal physiological or mechanicalforces that act on or by the device.

This disclosure also provides a method of treatment in the body vesselwith the device discussed herein. The method includes disposing thedevice within the body vessel; lengthening by a lengthening force on theouter layer or tubular body; and countering the lengthening force by acontraction force with the plurality of tensioners to maintain the outerlayer or tubular body in the radial direction. The method may furthercomprise allowing the device to biodegrade after the step of countering.

The step of lengthening by a lengthening force may comprise thelengthening force being perpendicular to the longitudinal axis. The stepof countering the lengthening force may comprise countering with a firstcontraction force in a first direction and a second contraction force ina second direction, the first and second directions being along thelongitudinal axis.

Further objects, features, and advantages of the invention will becomeapparent from consideration of the following description and theappended claims when taken in connection with the accompanied drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a an environmental side view of a medical device fortreatment in a body vessel in accordance with one embodiment of thepresent invention;

FIG. 1B is a blown-up partial view of the device of FIG. 1A in circleC₁;

FIG. 2A is an environmental side view of the device in accordance withanother embodiment of the present invention;

FIG. 2B is a blown-up partial view of the device in FIG. 2A in circleC₂;

FIG. 3A is a three-dimensional side view of the device in FIG. 1A;

FIG. 3B is a partial side view of the device in FIG. 3A in circle C₃;

FIG. 4A is a partial side view of the device in accordance with anotherembodiment of the present invention;

FIG. 4B is a blown-up partial view of the device in FIG. 4A in circleC₄;

FIGS. 5A-B are a delivery assembly for introducing the device in anyembodiment of the present invention discussed herein;

FIG. 6 is a flow diagram of one embodiment of treatment in the vesselwith the device in any embodiment in accordance with the presentinvention; and

FIGS. 7A-B depicts steps of the method in FIG. 6.

DETAILED DESCRIPTION

The present disclosure provides for a bioabsorbable implantable devicefor treatment in a vein or body vessel. The disclosure also provides fora method of treatment with the device. The materials, methods, andexamples disclosed are illustrative only and not intended to belimiting. The disclosed figures are not necessarily drawn to scale.

All publications, patent applications, patents, and other referencesmentioned herein are incorporated by reference in their entirety. Unlessotherwise defined, all technical and scientific terms used herein havethe same meaning as commonly understood by on of ordinary skill in theart to which this disclosure pertains. In case of conflict, the presentdocument and definition will control.

“Adjacent” referred to herein is near, near to, or in close proximitywith.

“Longitudinally” and derivatives thereof will be understood to meanalong the longitudinal axis of the device.

“Mechanical strength” referred to herein is the stiffness and strengthof a material. Mechanical strength may be measured in thecircumferential, radial, or longitudinal direction of the device.

The terms “proximal” and “distal” and derivatives thereof will beunderstood in the frame of reference of a physician using the device.Thus, proximal refers to locations closer to the physician and distalrefers to the locations farther away from the physician (e.g., deeper inthe patient's vasculature).

“Radially” and derivatives thereof will be understood to mean along aradial axis of the body vessel. Likewise, “radial force” and derivativesthereof will be understood to mean a force applied along the radialaxis.

FIGS. 1 and 2 depict two embodiments of the medical device discussedherein. The device may be disposed in a body vessel having a vessel wall11. The device also has a longitudinal axis A. In FIG. 1A, the devicehas an outer layer 12 comprising a first material and a plurality ofouter cells 14. The plurality of outer cells 14 are arranged in outercircumferential rows 16 with each outer cell 14 having an outerperimeter 18.

FIG. 1B depicts the details of the outer perimeter 18. FIG. 1B is ablown-up view of FIG. 1A around circle C₁. Each outer perimeter 18 mayhave a first outer cell edge 28 attached to a second outer cell edge 30at a proximal outer cell end 22. The first outer cell edge 28 and thesecond outer cell edge 30 define a distal outer angle 38. The outerperimeter 18 also may have a third outer cell edge 32 attached to afourth outer cell edge 34 at a proximal outer cell end 20. The thirdouter cell edge 32 and the fourth outer cell edge 34 make a proximalouter angle 36. The distal outer angle 38 is distal the proximal outerangle 36 along axis A.

Although FIGS. 1A-B do not depict details of the inner layer, it will beunderstood that the inner layer may be obscured by the outer layer 12 inthe two-dimensional views in FIGS. 1A-B. In FIGS. 2A-B, details of theinner layer are depicted. It will be understood that the outer layer maynormally obscure the inner layer in some views. The device alsocomprises an inner layer 40 having a second material being elastomericand a plurality of inner cells 42. The plurality of inner cells 42 arealso arranged in inner circumferential rows 44, with each inner cell 42having an inner perimeter 46.

As with FIG. 1B, FIG. 2B depicts the details of the inner perimeter 46.In FIG. 2B, the inner perimeter 46 has a first inner cell edge 56attached to a second inner cell edge 58 at a distal inner cell end 50.The first inner cell edge 56 and the second inner cell edge 58 define adistal inner angle 66. The inner perimeter 46 further has a third distalcell edge 60 attached to a fourth distal cell edge 62 at a proximalinner cell end 48. The third inner cell edge 60 and the fourth innercell edge 62 define a proximal inner angle 64. The distal inner angle 66is distal the proximal inner angle 64 along the longitudinal axis A.

In one embodiment, the distal outer angle 38 and the proximal outerangle 36 may be between about 50 to about 100 degrees. Likewise, thedistal inner angle 66 and the proximal inner angle 64 may be betweenabout 50 to about 100 degrees.

It will be understood that although FIGS. 1 and 2 depict features of theouter and inner layers, respectively, each embodiment may contain bothan outer and inner layer. Details of both layers are not shown in eachfigure for the sake of clarity. Further, at least one outer perimeter 18is attached to at least one inner perimeter 46. There may be about twoto about eight outer circumferential rows 16 in the outer layer 12 andinner circumferential rows 44 in the inner layer 40 in the longitudinaldirection. FIGS. 1A and 2A depict six circumferential rows each.

In FIGS. 1-2, the device comprises a plurality of tensioners 80 havingan extended length and a contracted length (discussed in further detailin FIG. 7). The plurality of tensioners 80 may be formed from the secondmaterial. In addition, each tensioner may be a filament, tubing, orbraided thread.

Each tensioner 80 is disposed within one inner cell 42, being attachedto the proximal inner cell end 48 and extending distally to the distalinner cell end 50 to apply a contraction force on at least one innercell 42. In one embodiment, each inner cell 42 has one tensioner 80being attached to the proximal inner cell end 48 and extending distallyto the distal inner cell end 50, although other distributions of thetensioners are possible.

The outer layer 12 and inner layer 40 may define a tubular body 68having a proximal end 70 extending to a distal end 72, and a lumen 74formed therethrough. The tubular body 68 has a length L_(TB). Thetubular body 68 comprises a collapsed state for delivery and an expandedstate for treatment in the body vessel. In the expanded state (FIGS.1-2), the outer layer 12 may experience or receive a lengthening forceand the tensioners 80 counter the lengthening force with a contractionforce to move from an extended length to a contracted length to maintaina radial force on the vessel wall.

As shown in FIG. 1B, the second and third outer cell edges (30 and 32,respectively) form a first outer cell apex 24. Additionally, the firstand fourth outer cell edges (28 and 34, respectively) form a secondouter cell apex 26. Correspondingly in FIG. 2B, the second and thirdinner cell edges (58 and 60, respectively) form a first inner cell apex52 and the first and fourth inner cell edges (56 and 62, respectively)form a second inner cell apex 54. Likewise, first outer and inner cellapices are each about 80 degrees to about 130 degrees in the expandedstate and the second outer and inner cell apices are each about 80degrees to about 130 degrees in the expanded state

In FIGS. 1A-B, the outer and inner perimeters (18 and 46, respectively)are rhombic. Each cell has a rhombic shape. In FIGS. 2A-B, the first andsecond outer cell apices and the first and second inner cell apices (52and 54, respectively) are arcuate.

FIG. 3A shows a detailed view of the outer and inner layers (12 and 40,respectively). In one embodiment, outer layer 12, the inner layer 40,and the tensioners 80 are co-extruded. In this embodiment, the firstmaterial and the second material are co-extruded to form the tubularbody. As a co-extrusion, the first and second materials may be formedtogether, attached. In this case, the first material of the outer layer12 may be removed as necessary to expose the second material of theinner layer 40. This removal could be done through any technique knownin the art, including ablating the outer layer.

Ablation is a technique where a portion of material is removed byvaporization, chipping, or melting to expose another portion ofmaterial. This technique may be used to remove any portion of materialdiscussed in this disclosure, including excess or unnecessary materialduring manufacturing.

Alternatively, the outer and inner layers may be formed separately. Suchlayers could be attached at a later time or as a secondary step via anymethod known in the art. Some examples include bonding, gluing, welding,or other similar methods to attach the outer and inner layers.

As shown in the blown-up partial view depicted in FIG. 3B around circleC₃, tensioner 80 forms a first angle 82 with the first inner cell edge56 and a second angle 84 with the second inner cell edge 58. The sum ofthe first and second angles (82 and 84, respectively) is about the sameas the distal inner angle. In one embodiment, the first and secondangles (82 and 84, respectively) are between about 25 to degrees about50 degrees in the expanded state.

The device may be formed from whatever first and second materials suitthe intended application. In one embodiment, the first material differsfrom the second material such that both materials contribute differentproperties to the device (e.g. mechanical strength). For example, thefirst material may be a high mechanical strength material. Such highmechanical strength material may provide strength and stiffness in thecircumferential, radial, or longitudinal directions during treatment.The high mechanical strength material may be a material selected fromthe group consisting of poly-L-lactide, poly-L-lactic acid,poly-D/L-lactic acid, and a co-polymer of poly lactic-co-glycolic acidand polycaprolactone. In one aspect, the high mechanical strengthmaterial is 100% poly-L-lactide.

Additionally, the second material may be elastomeric to provide acontraction force on the first material and the device. For example, theelastomeric material may form the tensioners and apply the contractionforce on the inner layer at the points where the tensioners connect withthe inner layer. In turn, this applies a force on the outer layer. Theelastomeric material may be polycaprolactone and range from about 100%polycaprolactone to about 10% polycaprolactone, wherein thepolycaprolactone may be a copolymer with another material. In oneaspect, the elastomeric material is about 50% polycaprolactone.

In one embodiment, the first and second materials are bothbiodegradable. In this embodiment, over time the entire device willbiodegrade within the body and will require no secondary removalprocedure. One skilled in the art will understand that the device couldalso be partially biodegradable, wherein either the first or secondmaterials may be biodegradable.

In an additional embodiment as shown in FIG. 4A-B, the device may have aplurality of filter struts 86 attached to the inner layer. As in FIG.4A, each filter strut 86 may have a proximal segment 78 attached to thedistal end 72 and extend distally to a distal segment 88 wherein alldistal segments 88 are gathered at a center point 76 along thelongitudinal axis. The distal segments 88 may be directed attached toeach other at the center 76. They could also be attached to each otherat other points.

FIG. 4B shows a blown-up view of the attachment of the proximal segment78 to the inner layer in circle C₄. Each proximal segment 78 may extenddirectly from one tensioner 80 at the distal inner cell end 50.Alternatively or additionally, the plurality of filter struts 86 mayattach between the proximal and distal ends (70 and 72, respectively).For example, the filter struts 86 may have a similar configuration asshown in FIG. 4A, but extend within the lumen 74. There may be more thanone set of filter struts throughout the device. For example, there maybe one set at the proximal end and one set at the distal end.

The device may have a plurality of filter struts 86 from about six toabout 12 filter struts. The filter struts 86 may be formed from anysuitable material, including the first material or the second material.The filter struts may be co-extruded with the tubular body or,alternatively, attached to the tubular body by any means known in theart.

The dimensions of the entire device could be changed to fit the intendedbody vessel. For example, the tubular body may have a length L_(TB) ofabout 25 millimeters to about 85 millimeters, or about 25 millimeters toabout 60 millimeters between the proximal and distal ends (70 and 72,respectively). In the event that filter struts are present, the filterstruts 86 could be about 25 millimeters to about 60 millimeters each inlength as well.

Further, in the event that filter struts are attached to the distal end72, the length of the tubular body and the filter strut 86 could beabout 30 millimeters each, resulting in a total length of about 60millimeters. The diameter of the tubular body would be about 35millimeters in the expanded state. Correspondingly, the diameter of thetubular body could be about 5 millimeters in the collapsed state,crimped or compressed.

FIGS. 5A-B depict a delivery assembly for delivering the device 10. Thedevice 10 may be delivered or retrieved by way of the Seldingertechnique. As shown, the delivery assembly 200 includes apolytetrafluoroethylene (PTFE) introducer sheath 202 for percutaneouslyintroducing an outer sheath 204 into a body vessel. Of course, any othersuitable material for the introducer sheath 202 may be used withoutfalling beyond the scope or spirit of the present invention.

The introducer sheath 202 may have any suitable size, for example,between about 3-FR to 8-FR. The introducer sheath 202 serves to allowthe outer sheath 204 and an inner member or catheter 206 to bepercutaneously inserted to a desired location in the body vessel. Theinner member may also include, for example, a stylet. The introducersheath 202 receives the outer sheath 204 and provides stability to theouter sheath 204 at a desired location of the body vessel. For example,the introducer sheath 202 is held stationary within a common visceralartery, and adds stability to the outer sheath 204, as the outer sheath204 is advanced through the introducer sheath 202 to a treatment area inthe vasculature. The outer sheath 204 has a body extending from aproximal end 216 to a distal end 210, the body being tubular andincluding a sheath lumen extending therethrough.

As shown, the assembly 200 may also include a wire guide 208 configuredto be percutaneously inserted within the vasculature to guide the outersheath 204 to the treatment area. The wire guide 208 provides the outersheath 204 with a path to follow as it is advanced within the bodyvessel. The size of the wire guide 208 is based on the inside diameterof the outer sheath 204 and the diameter of the target body vessel.

A needle may also be used. The needle may be used for percutaneouslyintroducing the wire guide into the patient's body through an accesssite. A cutting device 10 may also be used to expand the access site.

When the distal end 210 of the outer sheath 204 is at the desiredlocation in the body vessel, the wire guide 208 is removed and thedevice 10, having a proximal segment contacting a distal portion 212 ofthe inner catheter 206, is inserted into the outer sheath 204. The innercatheter 206 is advanced through the outer sheath 204 for deployment ofthe device 10 through the distal end 210 to treat the body vessel. Thecatheter 206 extends from a proximal portion 211 to a distal portion 212and is configured for axial movement relative to the outer sheath 204.

In this example, the distal portion 212 is shown adjacent to the device.Thus, before deployment, the device 10 is coaxially disposed within thelumen of the outer sheath 204 and removably coupled to the distalportion 212 of the catheter 206, or in the alternative, the device 10 ismerely pushed by, but not coupled to, the distal portion 212 of thecatheter 206.

The outer sheath 204 further has a proximal end 216 and a hub 218 toreceive the inner catheter 206 and device 10 to be advancedtherethrough. The size of the outer sheath 204 is based on the size ofthe body vessel in which it percutaneously inserts, and the size of thedevice 10.

In this embodiment, the device 10 and inner catheter 206 are coaxiallyadvanced through the outer sheath 204, following removal of the wireguide 208, in order to position the device 10 in the body vessel. Thedevice 10 is guided through the outer sheath 204 by the inner catheter206, preferably from the hub 218, and exits from the distal end 210 ofthe outer sheath 204 at a location within the vasculature whereocclusion is desired. Thus, the device 10 is deployable through thedistal end 210 of the outer sheath 204 by means of axial relativemovement of the catheter 206. In order to more easily deploy the device10 into the body vessel, the device 10 may have a lubricious coating,such as silicone or a hydrophilic polymer, e.g. AQ® Hydrophilic Coatingas known in the art.

Likewise, in this embodiment the device 10 may also be retrieved bypositioning the distal end 210 of the outer sheath 204 adjacent thedeployed device in the vasculature. The inner catheter 206 is advancedthrough the outer sheath 204 until the distal portion 212 protrudes fromthe distal end 210 of the outer sheath 204. The distal portion 212 iscoupled to a proximal end of the device 10, after which the innercatheter 206 is retracted proximally, drawing the device 10 into theouter sheath 204.

The device 10 has a collapsed state for delivery and an expanded statefor filtering once delivered to the desired location in the body vessel.In the collapsed state, the device 10 is disposed inside the deliveryassembly. The device 10 may be self-expanding or expandable to theexpanded state upon exiting the delivery assembly for filtering (asshown in FIG. 5B).

The assembly described above is merely one example of an assembly thatmay be used to deploy the device in a body vessel. Of course, otherapparatus, assemblies and systems may be used to deploy any embodimentof the device without falling beyond the scope or spirit of the presentinvention.

FIG. 6 shows a flow diagram of the steps of one method to treat the bodyvessel using the device. In step 90, the device may be disposed withinthe body vessel. The device may have any or all of the featuresdiscussed herein. In step 92, the device may lengthen by a lengtheningforce on the outer layer or tubular body. In step 94, the device maycounter the lengthening force with a contraction force from theplurality of tensioner to expand the outer layer or tubular body in theradial direction. If the device contains biodegradable material, in step96, the device may biodegrade.

FIGS. 7A-B depict the steps of the method in FIG. 6. In FIG. 7A, thedevice may lengthen by a lengthening force F_(L) on the tubular body 68.This lengthening force F_(L) may be an internal force of the device oran external force on the device as a result of natural physiology. Thislengthening force F_(L) may causes the outer layer to deform or relaxand increase the length of the elastomeric tensioners 80 from a defaultposition to an expanded length L_(E). This relaxation may cause theproximal and distal angles to decrease (64 and 66, respectively).

As a result in FIG. 7B, the tensioners 80 may apply a contraction forceon the inner layer of the tubular body 68. For example, the contractionforce may be a first contraction force F_(C1) in a first direction and asecond contraction force F_(C2) in a second direction. The first andsecond directions may be opposite from each other and along thelongitudinal axis. This contraction force may decrease the length of thetensioners 80 from the expanded length L_(E) to a contracted lengthL_(C).

The expanded and contracted lengths of the tensioners may not be thelongest and shortest lengths, respectively, that the tensioners mayhave. For example, the device may have a relaxed stated, where it is notdisposed within a body vessel and has no external forces acting on it.In this relaxed state, the tensioners may naturally assume theirshortest length. Contrastingly, the device may have a crimped ordelivery state where the device has a small diameter. In this state, thetensioners may assume their longest length. Instead, the expanded andcontracted lengths of the tensioners refer to those lengths when thedevice is implanted within a body vessel. Thus, these particular lengthsshould be understood in reference to each other and not to an absolutelongest or shortest length possible for the tensioners.

This contraction force may also increase the magnitude of the proximaland distal inner angles (64 and 66, respectively). Correspondingly, thismay increase the magnitude of the proximal and distal outer angles (48and 50, respectively). Finally, the contraction forces may result in anincreased radial force F_(R) on the vessel wall, which maintains theoutward tension of the device on the vessel wall. The radial force F_(R)may result from a circumferential force of each cell, as shown in FIG.7B. Even if the materials are biodegradable, the tensioners 80 mayassist in maintaining an outward radial force against the vessel wall.The contraction forces may act on the tubular body until at least thetime that the device is embedded into the vessel wall tissue throughendothelialization. Over time, part or all of the device may degrade andbe absorbed.

While the present invention has been described in terms of certainembodiments, it will be understood that the invention is not limited tothese disclosed embodiments and those having skill in the art may makevarious modifications without departing from the scope and purpose ofthe following claims.

The invention claimed is:
 1. A method of deploying a medical device in abody vessel having a vessel wall, the method comprising: disposing themedical device within the body vessel, the medical device having alongitudinal axis and comprising: an outer layer comprising a firstmaterial and a plurality of outer cells arranged in outercircumferential rows, each outer cell having an outer perimetercomprising a first outer cell edge attached to a second outer cell edgeat a distal outer cell end, defining a distal outer angle, and a thirdouter cell edge attached to a fourth outer cell edge at a proximal outercell end, defining a proximal outer angle, the distal outer angle beingdistal the proximal outer angle along the longitudinal axis; an innerlayer comprising a second material being elastomeric and a plurality ofinner cells arranged in inner circumferential rows, each inner cellhaving an inner perimeter comprising a first inner cell edge attached toa second inner cell edge at a distal inner cell end, defining a distalinner angle, and a third inner cell edge attached to a fourth inner celledge at a proximal inner cell end, defining a proximal inner angle, thedistal inner angle being distal the proximal inner angle along thelongitudinal axis, wherein at least one outer perimeter is attached toat least one inner perimeter, the outer and inner layers defining atubular body having a proximal end extending to a distal end and a lumenformed therethrough; and a plurality of tensioners having an extendedlength and a contracted length and comprising the second material, eachinner cell having one tensioner being attached to the proximal innercell end and extending distally to the distal inner cell end to apply acontraction force on the inner cell; lengthening the outer layer by alengthening force; and countering the lengthening force by thecontraction force to maintain a radial force on the vessel wall.
 2. Themethod of claim 1 wherein the step of lengthening the outer layercomprises the lengthening force being perpendicular to the longitudinalaxis.
 3. The method of claim 1 wherein the step of countering thelengthening force comprises countering with a first contraction force ina first direction and a second contraction force in a second direction,the first and second directions being along the longitudinal axis. 4.The method of claim 3 wherein the first direction and the seconddirection are opposite from each other.
 5. The method of claim 1 whereineach tensioner moves from the extended length to the contracted lengthto maintain a radial force on the vessel wall.
 6. The method of claim 1wherein the contraction force increases the proximal inner angle and thedistal inner angle.
 7. The method of claim 1 wherein the contractionforce increases the proximal outer angle and the distal outer angle. 8.The method of claim 1 wherein the first and second materials arebiodegradable.
 9. The method of claim 8 further comprising allowing themedical device to biodegrade after the step of countering thelengthening force.
 10. The method of claim 1 wherein the medical devicefurther comprises a plurality of filter struts attached to the innerlayer.
 11. The method of claim 10 wherein each filter strut comprises aproximal segment attached to the distal end and extending distally to adistal segment wherein all distal segments are attached to each other.